Leadized gasoline



De c. 5, 1933.

F. w. SULLIVAN. JR., ET AL 1,938,547

LEADIZED GASOLINE Filed March 21. 1932 92 &

I dime a K 17 Z jzezzezwkwm 3m (BM Atty Patented Dec. 5, 1933 UNITED STATES PATENT OFFICE LEADIZED GASOLINE Frederick W. Sullivan, Jr., Hammond, Ind., and Fred F. Diwoky, Chicago, Ill., assignor's to Standard Oil Company, Chicago, 11]., a corporation of Indiana Application March 21, 1932. Serial No. 600,222

12 Claims.

quantities as anti-knock substances in motor fuels. In general, these lead alkyl compounds are prepared by reacting an alkyl chloride or bromide with a lead alloy such as an alloy of sodium and lead. There are a number of other ways of making lead alkyl compounds all of which in general require the use of an alkyl chloride and an expensive metal such as sodium or magnesium or alloy thereof.

We have 'now found that hydrocarbon com pounds of lead can be prepared directly from metallic lead and hydrocarbons; we find that it is possible to dissociated hydrocarbons by means of an electric spark whereby free alkyl radicals are formed and that these free radicals will combine with lead.

Our process is characterized by providing a high tension electric arc of the order of 25,000 volts, between lead electrodes and maintained either in a body of liquid hydrocarbon or in a body of hydrocarbon vapors, the hydrocarbon being one which, when subjected to the action of the arc, dissociates to give free alkyl radicals. Thus, under the conditions of our invention, such dissociation of the hydrocarbons occurs in the region of the arc and in contact with metallic lead, either in fine particle form or as a lead fog, as will be more fully explained. These conditions, we find, are therefore appropriate to the immediate formation of significant quantities of alkyl compounds of lead by reaction of the lead with the free alkyl radicals. The lead compounds thus obtained can be recovered either in a pure state or in solution in the hydrocarbon liquid in which they are formed. v a

On the appended single sheet of drawings we have indicated two advantageous ways of carrying out our process. In Figure 1, we have diagrammatically shown suitable apparatus for carrying out our process when the decomposition occurs in vaporized hydrocarbon material. In Figure 2 we have shown an advantageous form of ap- 5 paratus for use in ourprocess when it is desired to carry out the decomposition within a body of liquid hydrocarbon.

Referring more particularly to Fig. 1 a reaction vessel 1 contains a body of liquid hydrocarbons, such as hexane or heptane. Above the liquid level of the hydrocarbon, shown at 3, we provide lead electrodes 4. The lead electrodes pass through the sides of the vessel 1 through insulating bushings 5. The electrodes are connected to a source of high voltage alternating current by current conductors 6. A heating coil 14 is provided in receiver 1 to facilitate vaporization of the hydrocarbon therein. At the top of the reaction vessel there is provided an outlet conduit 7 for reaction products.- Conduit '7 leads to condenser 8 terminating in a receiver 9. A vacuum pump, not shown, is connected to the receiver 9 by conduit 10 and condensed reaction products may be withdrawn from the receiver 9 through valved outlet 11. Cooling coils 12 are advantageously provided to maintain the contents of receiver 9 below a volatilizing temperature.

In the operation of the device shown in Figure 1, a hydrocarbon, which may be either liquid or gas, and which yields free alkyl radicals on electrothermal dissociation, is maintained in the reaction vessel 1. The system is preferably maintained under a reduced pressure, for example 1 to 5 millimeters of mercury absolute although higher pressures can be used. Under these conditions, a certain amount of liquid hydrocarbon will volatilize into the vapor space above the liquid level. Upon the institution of an are between the lead electrodes, as by the application of a high tension current at about 25,000 volts thereto, volatilized hydrocarbon in the vapor space above the liquid level is dissociated. At the same time a fog or mist of lead particles is generated from the lead electrodes. The hydrocarbon dissociation products contain free. alkyl radicals which immediately unite with the lead fog to form volatile lead-alkyl; compounds. These volatile lead-alkyl compounds together with undissociated hydrocarbon vapors pass upwardly into conduit 7, condense in condenser 8, and collect in receiver 9. It-is sometimes desirable although not essential, to provide receiver 9 with cooling means, such as refrigerator coils 12,'in order to keep the lead compounds in the liquid state under the low pressure conditions employed. These lead compounds are very volatile substances.

Since the lead alkyl compounds are formed at the expense of the lead electrodes, the latter contributing to the lead fog described above, we advance the electrodes during the course of the reaction so that the arcing distance between them remains approximately the same. As a rule, the arc is about 1 to 20 millimeters long. That is to say, the ends of the electrodes are spaced apart about 1 to 20 millimeters. We maintain this distance throughout the reaction by advancing the electrodes to compensate for loss of lead from their arcing surfaces. This may be done inany convenient manner.

When using relatively high boiling hydrocarbon liquids such as hexaneor heptane, it is sometimes advantageous to raise the temperature of the hydrocarbon liquid slightly to increase the vapor pressure of the liquid. This is easily done by passing a heating fluid through heating coil 14 within the reaction vessel. Likewise, if the heat of the arc causes too much volatization, a cooling fluid can be passed through coil 14 to restrain vaporization. The reaction product, which consists mainly of hydrocarbon compounds of lead, volatilized and condensed undissociated hydrocarbons, and uncondensible reaction products such as hydrogen, is cooled in condenser 8 to a temperature which insures the condensation of the lead-alkyl compounds as well as the undissociated hydrocarbon liquid. The uncondensible gases, such as hydrogen, pass out of the system through outlet 10.

The reaction products collected in receiver 9 consist very largely of lead-alkyl compounds dissolved in the condensed hydrocarbon fluid. When we wish to impart anti-knock qualities to a gasoline, we advantageously add to the gasoline the desired quantity of lead-alkyl compounds in solution in the hydrocarbon liquid as obtained in receiver 10. This obviates the necessity for recovering the lead compounds in a substantially pure state from the hydrocarbon liquid. The lead compounds can be recovered, however, in ways well known, for example by fractional distillation.

Our invention also provides a very convenient method of incorporating soluble lead compounds in gasoline itself. When we wish to do this we use gasoline as the hydrocarbon liquid in reaction vessel 1 and obtain a reaction product in receiver 9 consisting of condensed und'ecomposed gasoline in which the lead alkyl compounds are dissolved.

When using liquid hydrocarbons in the apparatus shown in Figure 1, the yield of lead-hydrocarbon compounds is a significant, though variable, quantity, depending, of course, upon such factors as the capacity of the apparatus, the rate of vaporization of the hydrocarbon liquid, the cross-sectional area of the lead electrodes and hence the amount of lead fog generated, the pressure in the system, and the particular hydrocarbon liquid chosen.

The product obtained in receiver 9 can be fractionally distilled to obtain the lead compounds in a substantially pure state and, when this is done, we advantageously recycle undissociated hydrocarbon. In this manner we are able to convert the larger portion of the original quantity of hydrocarbon material to lead compounds.

Cooler 12, in receiver 9 should be operated at such a temperature that no lead compounds collected in the receiver volatilize under the pressure conditions employed. When the ressure in the system is about 5 millimeters, the cooler should be at about 10 C.

When we wish to obtain a product consisting substantially of lead compounds free of undecomposed hydrocarbon material, we flnd it more advantageous to use normally gaseous hydrocarbons as the source of alkyl radicals. In this modiiication, we introduce gaseous hydrocarbons such as methane, ethane, propane or butane into the, reaction vessel 1 through valved inlet 13. Since these substances are gaseous, the system need not be under reduced pressure and cooling coil 12 is unnecessary. Product obtained in receiver 9 consists substantially of lead-hydrocarbon compounds, and undissoclated gaseous hydrocarbons leaving the receiver through outlet 10 can be recycled back to vessel 1. Hydrogen constitutes one of the reaction products obtained in the electrothermal dissociation and in the event that the hydrogen in the recycled hydrocarbon gases becomes too great, portions of the recycled gas can be vented to the atmosphere.

In Fig. 2, the reaction vessel 1 is provided with a valved inlet 13, lead electrodes 4, insulating bushings 5, and a reflux condenser 16. The reaction vessel is also provided with valved outlet 1'! and a gas conducting pipe 18 which terminates at a point immediately beneath the adjacent ends of the electrodes. A body of hydrocarbon liquid 2 is maintained in the reaction vessel in such a manner that the liquid level 3 of the hydrocarbon is above the electrodes.

High tension current leads 6 areprovided as in Fig. 1. h

In the operation of the device shown in Fig. 2 a body of hydrocarbon liquid, for example, hexane or pentane, is maintained in reaction vessel 1 and an electric are established between adjacent ends of electrodes 4. To assist in the initial establishment of the arc, we provide pipe 18 for the admission of a suitable gas such as hydrogen or ethylene. The hydrogen or ethylene, admitted to the space between the arcing surfaces of the electrodes, temporarily decreases the resistance to the passage of current across the arcing space which would otherwise exist due to the hydrocarbon liquid. The bubbles of hydrogen or ethylene thus enable the arc to start. After the arc has been established the flow of hydrogen or ethylene may be terminated and the arc will continue to function.

As soon as the arc is established, a certain amount of colloidal lead is formed in the body of hydrocarbon liquid as well as quantities of lead vapor. This is advantageous. The arc,

' when once established, dissociates the hydrocarbon liquid between the arcing surfaces with the liberation of free alkyl radicals. These combine at once with the lead in colloidal solution in the liquid or with the lead vapor from the electrodes. We also provide means to advance the electrodes so as to keep the arcing distance constant as the electrodes wear away.

The lead alkyl compounds formed remain dissolved in the body of hydrocarbon liquid and after a suflicient amount of lead is consumed we withdraw the reaction products through outlet 17. return hydrocarbon liquid which might be volatilized due to the heat of the arc.

As in the process described in connection with Fig. 1, we use a high tension current at about 25,000 volts or more. In the alternative method just described it is unnecessary to operate under a high vacuum. The process may be conducted under ordinary atmospheric pressure.

I When carrying out our process in accordance with the showing in Fig. 2, all that is necessary A reflux condenser 16 is provided to is to maintain the arc within a body of hydrocarbon liquid. It need not be heated.

In our invention we can use any hydrocarbon liquid or gas, including the olefin hydrocarbons such as ethylene or propylene, so long as the hydrocarbon is one which can be dissociated by an electric spark to liberate free alkyl radicals.

Having thus described our invention, what we claim is:

1. Theprocess of preparing hydrocarbon compounds of lead which comprises establishing a high tension arc within a body of hydrocarbon material of the type yielding free alkyl radicals on dissociation, immediately contacting the hydrocarbon dissociation products thus formed with metallic lead whereby the free alkyl radicals in said products combine with the lead to form hydrocarbon compounds of lead, and immediatelyremoving the latter from the zone of the arc.

2. The process of preparing hydrocarbon compounds of lead which comprises establishing a high tension are within a body of hydrocarbon gas of the type yielding free alkyl radicalson dissociation, immediate contacting the hydrocarbon dissociation products with metallic lead whereby the free alkyl radicals in said products combine with the lead to form hydrocarbon compounds of lead, and immediately removing the latter from the zone of the arc.

3. The process of preparing hydrocarbon compounds of lead which comprises establishing a high tension are within a body of a liquid hydrocarbon of the type yielding free alkyl radicals on dissociation, immediately contacting the hydrocarbon dissociation products with metallic lead whereby the free alkyl radicals in said products combine with the lead to form hydrocarbon compounds of lead, and withdrawing the resulting solution of lead-hydrocarbon compounds from the zone of the arc after the desired quantity of such compounds has been formed.

4. The process of preparing hydrocarbon compounds of lead which comprises establishing a high tension are between lead electrodes within a body of a hydrocarbon of the type which yields free alkyl radicals on dissociation thereby combining the free alkyl radicals thus formed with metallic lead and immediately removing the leadhydrocarbon compounds from the zone of the arc.

5. The process of preparing hydrocarbon compounds of lead which comprises establishing a high tension are between lead electrodes within a body of hydrocarbon gas of the type yielding free alkyl radicals on dissociation thereby combining the free alkyl radicals thus formed with metallic lead and immediately removing the leadhydrocarbon compounds from the zone of the arc.

6. The process of preparing hydrocarbon compounds of lead which comprises establishing a high tension arc between lead electrodes immersed in a body of a liquid hydrocarbon of the type yielding free alkyl radicals on dissociation, thereby combining the free alkyl radicals thus formed with metallic lead and withdrawing the resulting solution of lead-hydrocarbon compounds from the zone of the are after the desired quantity of such compounds has been formed.

'7. The process of preparing a hydrocarbon liquid containing organic compounds of lead dissolved therein which comprises dissociating a vaporized hydrocarbon by a high tension arc in the presence of metallic lead, the hydrocarbon being one which yields free alkyl radicals on such dissociation, whereby hydrocarbon compounds of lead are formed, and then condensing the reaction products.

8.The process of preparing a hydrocarbon liquid containing organic compounds of lead dissolved therein which comprises dissociating a hydrocarbon gas by a high tension arc in the presence of metallic lead, the hydrocarbon being one which yields free alkyl radicals on such dissociation whereby hydrocarbon compounds of lead are formed, and then condensing the reaction products.

9. The process of preparing a hydrocarbon liquid containing organic compounds of lead dissolved therein which comprises maintaining a body of a liquid hydrocarbon, and establishing a high tension arc therein in the presence of metallic lead to dissociate a portion of said hydrocarbon to form free alkyl radicals, whereby hydrocarbon compounds of lead are formedand dissolve in the main body of hydrocarbon liquid, the hydrocarbon being one which yields free alkyl radicals on such dissociation and withdrawing the resulting hydrocarbon solution of leadhydrocarbon compounds from the zone of the arc after the desired quantity of such compounds has been formed. Y

10. The process of preparing a hydrocarbon liquid containing organic compounds of lead dissolved therein which comprises dissociating' a vaporized hydrocarbon by a high tension are maintained between lead electrodes, the hydrocarbon being one which yields free alkyl radicals on such dissociation, whereby hydrocarbon compounds of lead are formed, and then condensing the reaction products.

11. The process of preparing a hydrocarbon liquid containing organic compounds of lead dissolved therein which comprises dissociating a hydrocarbon gas by a. high tension are maintained between lead electrodes, the hydrocarbon being one which yields free alkyl radicals on such dissociation whereby organic compounds of lead are formed, and then condensing the reaction products.

12. The process of preparing a hydrocarbon liquid containing organic compounds of lead dissolved therein which comprises maintaining a body of a liquid hydrocarbon and establishing a high tension arc therein between lead electrodes to dissociate a portion of said hydrocarbon to form free alkyl radicals, whereby hydrocarbon compounds of lead are formed and dissolved in the main body of hydrocarbon liquid, the hydrocarbon being one which-yields free alkyl radicals on such dissociation, and withdrawing the resulting hydrocarbon solution of lead-hydrocarbon compounds from the zone of the are after the desired quantity of such compounds has been formed.

FREDERICK W. SULLIVAN, JR. FRED F. DIWOKY. 

